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GSE49918
Escherichia coli
12 Downloadable Samples
Affymetrix E. coli Genome 2.0 Array (ecoli2)
Description
As part of our studies on the biological functions of polyamines we have used a mutant of Escherichia coli that lacks all the genes for polyamine biosynthesis for a global transcription analysis on the effect of added polyamines. The most striking early response to polyamine addition is the increased expression of the genes for the glutamate dependent acid resistance system (GDAR) that is essential for the survival of bacteria when passing through the acid environment of the stomach. Not only were the two genes for glutamate decarboxylases (gadA and gadB) and the gene for glutamate --aminobutyrate antiporter (gadC) induced by polyamine addition, but also the various genes involved in the regulation of this system were induced. We confirmed the importance of polyamines for the induction of the GDAR system by direct measurement of glutamate decarboxylase activity and acid-survival. Effects of deletions of the regulatory genes in the GDAR system and on the effects of overproduction of two of these genes were also studied. Strikingly, overproductions of the alternate sigma factor rpoS and of the regulatory gene gadE resulted in very high levels of glutamate decarboxylase and almost complete protection against acid stress even in the absence of any polyamines. Thus, these data show that a major function of polyamines in E. coli is protection against acid stress by increasing the synthesis of glutamate decarboxylase, presumably by increasing the levels of the rpoS and gadE regulators.
Publication Title
Polyamines are critical for the induction of the glutamate decarboxylase-dependent acid resistance system in Escherichia coli.
Sample Metadata Fields
Treatment
View Samples- Escherichia coli
- 6 Downloadable Samples
- Affymetrix E. coli Genome 2.0 Array (ecoli2)
Description
Glutathionylspermdine synthetase/amidase (Gss) and the encoding gene (gss) have only been described in two widely separated species; namely Escherichia coli and several members of the Kinetoplastida phyla. In the present paper we have studied the species distribution more extensively. It is striking that all of the 75 Enterobacteria species that has been sequenced contain sequences with very high degree of homology to the E. coli Gss protein. Although homologous sequences are also present in various other bacteria, in contrast to Enterobacteria they are not present in all species of a given phyla. As previously reported homologous sequences were found in all five species of Kinetoplastids tested (including Trypansosma cruzi), but it is striking that comparable sequences are not found in a variety of invertebrate and vertebrate species, Archea and plants. Studies in E. coli show that the highest accumulation of glutathionylspermidine is found in stationary phase cultures where most of the intracellular spermidine is converted to glutathionylspermidine. However, even in log phase cells there is some formation of glutathionylspermidine, and isotope exchange experiments show that there is a rapid exchange between glutathionylspermidine and intracellular spermidine. We have not been able to define a specific physiologic function for glutathionylspermidine, but microarray studies comparing gss+ and -gss strains of E. coli show that a large number of genes are either upregulated or downregulated by the loss of the gss gene.
Publication Title
Escherichia coli glutathionylspermidine synthetase/amidase: phylogeny and effect on regulation of gene expression.
Sample Metadata Fields
No sample metadata fields
View Samples- Escherichia coli
- 24 Downloadable Samples
- Affymetrix E. coli Genome 2.0 Array (ecoli2)
Description
To study the physiological roles of polyamines, we have carried out a global microarray analysis on the effect of adding polyamines to an Escherichia coli mutant that lacks polyamines because of deletions in the genes in the polyamine biosynthetic pathway. Previously, we have reported that the earliest response to the polyamine addition is the increased expression of the genes for the glutamate dependent acid resistance system (GDAR). We also presented preliminary evidence for the involvement of rpoS and gadE regulators. In the current study further confirmation of the regulatory roles of rpoS and gadE is shown by a comparison of genome-wide expression profiling data from a series of microarrays comparing the genes induced by polyamine addition to polyamine-free rpoS+/gadE+ cells with genes induced by polyamine addition to polyamine-free rpoS and gadE cells. The results indicate that most of the genes in the E. coli GDAR system that are induced by polyamines require rpoS and gadE. Our data also show that, gadE is the main regulator of GDAR and other acid-fitness-island genes. Both polyamines and rpoS are necessary for the expression of gadE genes from the three promoters of gadE (P1, P2 and P3). The most important effect of polyamine addition is the very rapid post-transcriptional increase in the level of RpoS sigma factor. Our current hypothesis is that polyamines increase the level of RpoS protein, and that this increased RpoS level is responsible for the stimulation of gadE expression, which in turn induces the GDAR system in E. coli.
Publication Title
Polyamines Stimulate the Level of the σ38 Subunit (RpoS) of Escherichia coli RNA Polymerase, Resulting in the Induction of the Glutamate Decarboxylase-dependent Acid Response System via the gadE Regulon.
Sample Metadata Fields
Treatment
View Samples- Saccharomyces cerevisiae
- 13 Downloadable Samples
- Affymetrix Yeast Genome S98 Array (ygs98)
Description
The naturally occurring polyamines putrescine, spermidine or spermine are ubiquitous in all cells. Although polyamines have prominent regulatory roles in cell division and growth, precise molecular and cellular functions are not well established in vivo. In this work we have performed a microarray experiment in a polyamine mutant (delta-spe3 delta-fms1) strain to investigate the responsiveness of yeast genes to supplementation with spermidine and spermine. Expression analysis identified genes responsive to the addition of either excess spermidine (10-5 M) or spermine (10-5 M) compared to a control culture containing 10-8 M spermidine. 247 genes were up-regulated >2-fold, and 11 genes were up-regulated more than 10-fold after spermidine addition. Functional categorization of the genes showed induction of transport related genes, and genes involved in methionine, arginine, lysine, NAD and biotin biosynthesis. 268 genes were down-regulated more than 2-fold, and 6 genes were down-regulated more than 8-fold after spermidine addition. A majority of the down-regulated genes are involved in nucleic acid metabolism and various stress responses. In contrast, only few genes (18) were significantly responsive to spermine. Thus, results from global gene expression profiling demonstrate a more major role for spermidine in modulating gene expression in yeast than spermine.
Publication Title
Microarray studies on the genes responsive to the addition of spermidine or spermine to a Saccharomyces cerevisiae spermidine synthase mutant.
Sample Metadata Fields
Treatment
View Samples- Homo sapiens
- 9 Downloadable Samples
- Affymetrix Human Genome U133A Array (hgu133a)
Description
Among B-cell lymphomas mantle cell lymphoma (MCL) has the worst prognosis. By using a combination of genomic and expression profiling (Affymetrix GeneChip Mapping 10k Xba131 and U133 set), we analysed 26 MCL samples to identify genes relevant to MCL pathogenesis and that could represent new therapeutic targets. Recurrent genomic deletions and gains were detected. Genes were identified as overexpressed in regions of DNA gain on 3q, 6p, 8q, 9q, 16p and 18q, including the cancer genes BCL2 and MYC. Among the transcripts with high correlation between DNA and RNA, we identified SYK, a tyrosine kinase involved in B-cell receptor signalling. SYK was amplified at DNA level, as validated by fluorescence in situ hybridisation (FISH) analysis, and overexpressed at both RNA and protein levels in the JeKo-1 cell line. Low-level amplification, with protein overexpression of Syk was demonstrated by FISH in a small subset of clinical samples. After treatment with low doses of the Syk inhibitor piceatannol, cell proliferation arrest and apoptosis were induced in the cell line overexpressing Syk, while cells expressing low levels of Syk were much less sensitive. A combination of genomic and expression profiling suggested Syk inhibition as a new therapeutic strategy to be explored in lymphomas.
Publication Title
Genomic and expression profiling identifies the B-cell associated tyrosine kinase Syk as a possible therapeutic target in mantle cell lymphoma.
Sample Metadata Fields
No sample metadata fields
View Samples- Mus musculus
- 15 Downloadable Samples
- Affymetrix Mouse Genome 430 2.0 Array (mouse4302)
Description
We have previously shown that rheumatoid factors (RF) produced by Fas-deficient autoimmune-prone mice typically bind autologous IgG2a with remarkably low affinity. Nevertheless, B cells representative of this RF population proliferate vigorously in response IgG2a/chromatin immune complexes through a mechanism dependent on the sequential engagement of the BCR and Toll-like receptor 9 (TLR9). To more precisely address the role of both receptors in this response, we analyzed the signaling pathways activated in AM14 B cells stimulated with these complexes. We found that the BCR not only serves to direct the chromatin complex to an internal compartment where it can engage TLR9 but also transmits a suboptimal signal that in combination with the signals emanating from TLR9 leads to NF?B activation and proliferation. Importantly, engagement of both receptors leads to the upregulation of a group of gene products, not induced by the BCR or TLR9 alone, that include IL-2. These data indicate that autoreactive B cells, stimulated by a combination of BCR and TLR9 ligands, acquire functional properties that may contribute to the activation of additional cells involved in the autoimmune disease process.
Publication Title
Functional outcome of B cell activation by chromatin immune complex engagement of the B cell receptor and TLR9.
Sample Metadata Fields
No sample metadata fields
View Samples- Mus musculus
- 7 Downloadable Samples
- Affymetrix Mouse Gene 2.0 ST Array (mogene20st)
Description
This SuperSeries is composed of the SubSeries listed below.
Publication Title
Unlinking an lncRNA from Its Associated cis Element.
Sample Metadata Fields
Specimen part, Cell line
View Samples- Mus musculus
- 7 Downloadable Samples
- Affymetrix Mouse Gene 2.0 ST Array (mogene20st)
Description
Transcriptome analysis of effect of Lockd knockout on cells
Publication Title
Unlinking an lncRNA from Its Associated cis Element.
Sample Metadata Fields
Specimen part
View Samples- Homo sapiens
- 40 Downloadable Samples
- Affymetrix Human Exon 1.0 ST Array [transcript (gene) version (huex10st)
Description
This SuperSeries is composed of the SubSeries listed below.
Publication Title
Molecular characterization of choroid plexus tumors reveals novel clinically relevant subgroups.
Sample Metadata Fields
Specimen part
View Samples- Homo sapiens
- 40 Downloadable Samples
- Affymetrix Human Exon 1.0 ST Array [transcript (gene) version (huex10st)
Description
Gene expression was assessed in a cohort of 40 choroid plexus tumors isolated from fresh-frozen tissue. We investigated unique expression patterns among tumor subgroups and refined the classification of choroid plexus tumors according to gene expression intensities.
Publication Title
Molecular characterization of choroid plexus tumors reveals novel clinically relevant subgroups.
Sample Metadata Fields
Specimen part
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